The uncertain history of land snails on Barbados: Implications for conservation

There is a growing need to document and conserve molluscan biodiversity, both for scholarly reasons and for public benefit. While the pursuance of these goals necessarily relies on historical records, the accuracy of such records is often taken for granted. We analyzed six previously published lists of land snails on the island of Barbados, and we compared them with results from our own field survey and our study of institutional collections. The current fauna contains six endemic species. Another endemic, Bulimulus fuscus, is probably extinct, and the status of two additional endemics, Lucidella barbadensis and Pseudopineria barbadensis, is unknown. Our total of 22 resident species is close to the total number of confirmed species collected by three earlier workers dating from 1862, but there are considerable differences in the four lists. When any one list is compared with any one of the others, each contains from one to six species that are absent from the other. Altogether, we confirm 31 species as present on Barbados at some time in the period 1862 to the present, compared with a total of 58 species reported by earlier workers. Our analysis allows us to confirm just 23 of the 37 species reported by Brown in 1903, whose list is the basis for a widely consulted conservation reference. By examining institutional collections and tracking down all pertinent literature, we discovered numerous errors of identity, locality and taxonomy. Adding to the task facing modern workers is the finding that at least 136 species names have been used to refer to 38 valid taxa, as a result of misidentifications, synonyms and genus/species combinations. We conclude that indications of historical trends in snail diversity should be treated with caution until critically evaluated.